The present invention relates to a rubber stopper for a waterproof connector and more particularly to improvements in rubber stoppers for waterproof connectors, which rubber stopper is inserted into the terminal receiving hole of a connection-terminal holding chamber of a connector housing in order to hermetically seal the connection-terminal holding chamber in a liquid-tight fashion.
Heretofore, connectors of various types have been used for connecting electric wires. Waterproof connectors designed to prevent the penetration of water and the like from the outside are fitted with waterproofing rubber stoppers for preventing rainwater and the like from penetrating into the connectors by hermetically sealing the gap between an electric wire and the inside wall surface of the terminal receiving hole of the connection-terminal holding chamber (hereinafter also called "cavity") of, for example, a connector housing in a liquid-tight fashion.
Japanese Utility Model Unexamined Publication No. Sho. 61-8971, for example, discloses a rubber stopper for a waterproof connector of the sort mentioned above. FIG. 1 schematically illustrate the structure of such a rubber stopper for a waterproof connector, wherein a rubber stopper 6 for a waterproof connector comprises a first half portion having a cylindrical terminal pressure-fitting portion 9, and a second half portion having a sealing portion 8 continuous to the terminal pressure-fitting portion 9. Further, parallel sealing protrusions 8a, 8b, 8c are formed in the sealing portion 8.
A pair of plate-like ribs 7a, 7b gradually rising toward to the top of the sealing protrusion 8a from the front end edge are formed integrally with the terminal pressure-fitting portion 9 and the sealing portion 8 on the outer periphery of the terminal pressure-fitting portion 9. The upper plate-like rib 7a is formed so that it is prevented from interfering with the pressure-fitting piece 4 of a connecting terminal 3, whereas the first half portion of the lower plate-like rib 7b is compressed by the pressure-fitting piece 4 and fitted to the connecting terminal 3. Consequently, the electric wire 5 is fitted into the rubber stopper 6 for a waterproof connector in a liquid-tight fashion.
When the rubber stopper 6 for a waterproof connector is inserted into the cavity 2 of the connector housing 1, the tilted plate-like ribs 7a, 7b are brought into contact with the terminal receiving hole of the cavity 2 so as to automatically adjust the central position even though the center of the rubber stopper 6 shifts from the center of the cavity 2. Even when the sealing protrusions 8a, 8b, 8c are forced in while being inserted obliquely because of the lack of uniformity of loading force, the plate-like ribs 7a, 7b act like springs when the loading force is removed and are able to make the sealing portion 8 properly function by correcting the posture of the sealing protrusions 8a, 8b, 8c.
In the case of such a waterproofing rubber stopper 6 as disclosed in Japanese Utility Model Unexamined Publication No. Sho. 61-8971, the connecting terminal 3 may be pressure-fitted slantwise to the rubber stopper 6 for a waterproof connector or the rubber stopper 6 for a waterproof connector may be inserted obliquely into the terminal receiving hole of the cavity 2, which forces part of sealing portion 8 to rub itself against the inside wall surface 2a of the terminal receiving hole. As a result, the rear sealing protrusions 8b, 8c excluding the sealing protrusion 8a become twisted as shown in FIG. 2.
When the connecting terminal 3 is pressure-fitted to the rubber stopper 6 for a waterproof connector, there is the possibility that the pressure-fitting piece 4 injures the plate-like ribs 7a, 7b, thus impairing the function of the plate-like ribs 7a, 7b.
Therefore, the adhesion of the sealing protrusions 8 of the rubber stopper 6 for a waterproof connector to the inside wall surface of the terminal receiving hole of the connector housing 1 is spoiled and this may deteriorate the sealing performance originally intended to hermetically seal the interior of the connecting housing 1 in a liquid-tight fashion.